1. Field of the Invention
The present invention relates to agricultural cultivators used to work the soil in fields. Typically, such cultivators include a tool bar mounted on a tractor or other vehicle to extend transversely thereto and a number of sub-assemblies mounted on the tool bar along its length. Each of the sub-assemblies includes cultivating implements and is intended to work a respective furrow in the field.
Although generally parallel, the rows in the field deviate from true parallelism in both vertical and transverse horizontal directions. Thus, while cultivators of this type allow simultaneous cultivation of a number of rows upon a single pass of the tractor across the field, they are somewhat inefficient in that the portions of the rows which deviate from parallelism are improperly or incompletely cultivated.
Accordingly, there has been a need for a cultivator which allows complete and proper cultivation of a number of rows simultaneously and which is still relatively uncomplicated and practical to manufacture.
2. Description of the Prior Art
U.S. Pat. No. 3,080,930 to Morkoski et al discloses a cultivator including two tool bars extending outwardly at opposite sides of a central support. Each of the tool bars can tilt with respect to the support about a single pivot axis extending longitudinally with respect to the vehicle to accommodate the gross vertical contours of the ground. However, there is no provision for accomodation of fine deviations, either vertical or horizontal, between the adjacent rows being cultivated by the various sub-assemblies on a tool bar.
The Morkoski et al device also includes means for raising the entire group of sub-assemblies on the tool bar to an inoperative position. The entire tool bar can be swung forward so that it extends longitudinally with respect to the tractor for transport, and the innermost sub-assembly can be raised higher than the others to clear the tractor wheel during such motion.
U.S. Pat. No. 2,882,982 to Hobbs shows a plurality of implements arranged in pairs on a large frame. The implements are rake-like devices intended to ride on the ridges of the rows in the fields to clear away excess soil from the lower portions of plants such as peanut plants. The implements of each pair are pivotally mounted so that they can diverge to allow passage of a rock or other obstruction therebetween.
However, the pivoting is of the single axis type which causes tilting of the implements with respect to the frame. While this might be acceptable in implements of the type described, it is not suitable for implements which work the ground. Furthermore, since the implements ride on the ridges rather than in the furrows, springs are required to return the implements to their normal positions after they have diverged.
The implements can also pivot vertically. However, during forward motion of the tractor, this pivotal movement is also of the single axis type.
U.S. Pat. No. 2,751,834 to Hines et al discloses a weeder in which an entire set of implements can float vertically as a unit. No independent floating of individual implements is permitted, nor is horizontal movement permitted.